Secondary Growth in Dicot Stem

Secondary growth in a dicot stem is carried out jointly by the vascular cambium and the cork cambium. The vascular cambium first forms as a continuous ring inside the stem and begins cutting off new cells - secondary xylem toward the inside, secondary phloem toward the outside - thickening the stem's vascular core year after year. As the stem's girth increases beyond what the epidermis can stretch to cover, a second lateral meristem, the cork cambium, differentiates in the outer tissues and builds a new protective periderm to take over from the epidermis. The sections that follow trace this process in order: how the vascular cambium itself originates and is organised, how it functions to lay down wood and bast, how s …